The present series of inventions was prompted by the need to decrease the exposure of healthcare workers to potentially harmful needle sticks which, as detailed in the inventors"" recent disclosure (U.S. Pat. No. 5,478,328 in 1995), pose the risk of infection with diseases such as hepatitis and AIDS. All too commonly, inadvertent needle sticks occur with needles that are being used for, or have been used for, penetrating a diaphragm. The varied uses of such needle/diaphragm combinations include: (a) withdrawing from or injecting into a medication vial, collection tube, or fluid bag; (b) injecting or withdrawing medications or fluids via tubing attached to an intravenous catheter.
The common features of the present series of inventions include needle/diaphragm combinations wherein:
(a) xe2x80x9csafe yet penetratingxe2x80x9d needles, such as those illustrated, in part, in our prior patent (U.S. Pat. No. 5,478,328) and claimed herein, are designed to provide a compromise between xe2x80x9cpenetrating but dangerousxe2x80x9d sharp needles of traditional systems and newer xe2x80x9csafe but nonpenetratingxe2x80x9d blunt cannulae of needleless blunt-cannula systems (described below). The inventive needles are designed to decrease the likelihood of harmful puncture of the skin of a healthcare worker (compared to that associated with a traditional needle) by one or both of the following:
1) lessening the pointedness of the tip;
2) providing one or more recessed orifices as opposed to an open tip;
(b) the xe2x80x9cstrong yet penetrablexe2x80x9d diaphragms of the present disclosures are a compromise between the xe2x80x9cstrong but (relatively) impenetrablexe2x80x9d and the xe2x80x9cpenetrable but weakxe2x80x9d extremes described in the prior art (described below). They are designed to:
1) provide an intact covering or plug with a section that, at the time of clinical use, can be pierced with greater penetrability than a conventional diaphragm (which requires penetration by a traditional xe2x80x9cpenetrating but dangerousxe2x80x9d sharp-tip needle);
2) have the integrity and long-term shelf-life approximate to that of a conventional diaphragm and thus maintain the sterility of the enclosed contents for months or years prior to the first clinical usage of the needle/diaphragm combination;
3) have the versatility of a conventional diaphragm (i.e., be able to cover openings with a wide range of diameters as may be found on injection ports, bottle tops, etc.);
4) provide a snug, secure fit for the needle or cannula which pierces it and thereby prevent leakage and dislodgement;
5) provide resealing properties after needle or cannula removal that enable the diaphragm to maintain its integrity and hence the sterility of the underlying contents for a satisfactory duration.
In addition, Disclosure #II of the three-part series introduces the concept of and means of a xe2x80x9cconvertingxe2x80x9d mechanism for modifying the diaphragm immediately prior to its first penetration for clinical use. This converts a strong diaphragm which otherwise would not be so readily penetrable by a given xe2x80x9csafexe2x80x9d needle or cannula to a diaphragm which can be used in combination with said needle or cannula. The conversion may be accomplished by utilizing a device to puncture and/or slit the diaphragm (herein called a xe2x80x9cconvertorxe2x80x9d).
In addition, Disclosure #III of the three-part series introduces the concept of and means of providing reversible compression of a prechannelled or preweakened diaphragm. This enables one to ensure effective closure of a preslit or preweakened region before a diaphragm has been penetrated by a needle or cannula and, in many embodiments, restoration of the ancillary pressure may secure effective closure even after penetration.
As alluded to above, prior to the present invention, two extremes of needle/diaphragm combinations have been available: 1) Strong Diaphragm/ Dangerous Needle; or 2) Weak Diaphragm/Safe Cannula. These are described below:
1. Strong Diaphragm/Dangerous Needlexe2x80x94It traditionally was felt that, in virtually all settings, needle insertion through a diaphragm necessitated the use of a sharp needle. Known hypodermic needles for use with penetrating diaphragms typically have:
(a) a sharp point;
(b) an open tip.
Such needles have cutting points, formed by a beveled cut typically at an angle of approximately 45xc2x0 (or less) to the longitudinal axis of the needle shaft with an opening created at the junction of the beveled edge and the needle bore. Unfortunately, these features pose a threat to anyone who comes into contact with a used needle. The sharp point increases the likelihood of skin puncture; as evidenced by the large number of injuries, relatively little force is needed to penetrate the skin during an inadvertent stick with a sharp needle. The open tip can house infected fluid or tissue (herein called an inoculum); this increases the likelihood that a needle stick will result in disease transmission. The sharp-point, open-tip construction not only increases the risk of injury to a healthcare worker during usage but also increases the likelihood of accidental injury during recapping as a consequence of missing the cap or actually piercing the side of the cap.
2) Weak Diaphragm/Safe Cannulaxe2x80x94The newly designed xe2x80x9cneedlelessxe2x80x9d blunt-cannula systems (e.g., the InterLink System, Baxter Healthcare Corp., Deerfield Ill. in collaboration with Becton-Dickinson Co., Franklin Lakes N.J.; and the Lifeshields system, Abbott Laboratories, Abbott Park Ill.) contain a diaphragm that is modified at the time of manufacture to such a degree that it is penetrable by an xe2x80x9cabsolutelyxe2x80x9d blunt-tipped cannula (with an end that typically is flat or hemispherical, and never with less than a 75xc2x0 angle to the longitudinal axis of the cannula shaft). The manufacture of the diaphragm (herein called a xe2x80x9cblunt-cannula diaphragmxe2x80x9d) has been taught within the prior decade as follows:
(a) cutting a slit into the central portion of the diaphragm with a knife (xe2x80x9cpreslittingxe2x80x9d) (Jepson, Dudaran, and Finley WO89/06553 and WO90/11108 in 1989/90xe2x80x94Baxter).
(b) reinforcing such a preslit diaphragm by covering the main plug with a thin diaphragm portion and using a metal ferrule which remains permanently in place for securing the inner and outer members of the stopper assembly together (Hook U.S. Pat. No. 5,328,041 in 1994xe2x80x94Abbott). In justifying the need for his more complex process (which includes two stopper members and a ferrule), the inventor stated that this was required to maintain sterility of the contents of vials covered with a preslit diaphragm: xe2x80x9cthe same prepierced construction used in prepierced reseals cannot be implemented for the stoppers on vials because of sterility and shelf-life degradation questions.xe2x80x9d
(c) molding the diaphragm in two pieces which are joined by a penetrable hinged region (Grabenkort U.S. Pat. No. 5,403,293 in 1995xe2x80x94Abbott). Although Grabenkort claimed that his method of xe2x80x9ccompression molding allows the tolerances at the hinged region to be better controlled than the alternate method of cutting a slit into a rubber diaphragm (as originally described in a patent assigned to Baxter), the procedure to accomplish this appears to be more complicated as it involves the production of a stiff annular collar having a first and second annular flange.
(d) using ultrasonic heating to create a weakened portion that extends at least partially through the diaphragm""s midsection. The horn and anvil of the mounting device conduct heat away from the outer surfaces, thereby allowing them to remain continuous and unbroken (Helgren U.S. Pat. No 5,403,525 in 1995xe2x80x94Abbott).
Review of the earlier prior art shows that the use of a more readily penetrable diaphragm was taught 30 years previously, but none of the inventions of the prior art was designed to facilitate passage of a xe2x80x9csafexe2x80x9d needle as described in the present invention. Wimmer (U.S. Pat. No. 3,653,528) taught a means of creating an indentation in the outer surface to facilitate piercing without coring by a standard hypodermic needle. Sandhage (U.S. Pat. No. 2,906,423 in 1959) described a preslit diaphragm which was puncturable by a round-tip plastic xe2x80x9cneedlexe2x80x9d which was so blunt that it was also able to be inserted into the teat of a cow to inject medication for the treatment of mastitis; however, this required lubricant to xe2x80x9cfill up the cut slitxe2x80x9d after needle entry xe2x80x9cto aid in preventing the entry of contaminant organisms.xe2x80x9d Ogle (U.S. Pat. No. 5,060,812) described diaphragms which were modified to such a degree that they were penetrable by a syringe tip or nozzle (as opposed to a needle or cannula). Garrett (U.S. Pat. No. 4,197,848 in 1980) described a resilient, impermeable membrane for a urinary irrigation system, wherein said membrane had a normally closed, resiliently deformable slit. Said slit was maintained closed by compression, but was penetrable by the blunt end of a syringe. Baxter, the assignee of that invention, noted in a subsequent disclosure (WO 90/11103) that there was still a need for a preslit injection site which xe2x80x9cwill reliably reseal . . . .xe2x80x9d
Although the blunt-cannula diaphragms of the Baxter and Abbott needleless systems tend to self-seal after blunt cannula insertion, they do not guarantee adequate shelf-life and sterility in all contexts:
a) Because they require an appreciable degree of prechannelling or weakening at the time of manufacture, they have not been recommended for prolonged drug storage even prior to first clinical use and especially after they have been penetrated by a needle or cannula. Even in the prior art configuration in which the preslit extends only partway through the blunt-cannula diaphragm, xe2x80x9cthe end of the blunt cannula will be used to tear through the remainder of the sealing member.xe2x80x9d (WO 90/11103) This necessitates a very weak xe2x80x9ctearablexe2x80x9d portion which may restrict shelf-life, and it leads to the potential for poor resealing as a result of the tearing process. This has led to modifications such as the two stopper members and ferrule described above (Hooks U.S. Pat. No. 5,328,041) or an extra valve which serves to reinforce the potentially incompetent site of needle/cannula entry and thereby reduce the risk of leakage (Brimhall U.S. Pat. No. 5,242,393). Despite these modifications, bottles and bags that either house or transfer medication and/or fluids for extended periods of time typically are not equipped for use with the Baxter or Abbott blunt-cannula systems.
b) It is recommended that such blunt-cannula diaphragms be used only with specially designed blunt cannulae since they are prone to damage by sharp needles. Said cannulae have been described as having distal ends which are completely blunt (90xc2x0 degree angle to the longitudinal axis), arcuate, or hemispherical or as having a lead post which extends beyond the end of the cannula (to guide insertion) or a taper with at least a 75xc2x0 angle to the longitudinal axis. Greater tapers and actual points were avoided in large part because of the preslit/preweakened diaphragm""s susceptibility to damage. The inventors of needleless systems also proposed the use of conventional lubricant xe2x80x9cto further reduce the friction and lower the insertion force required.xe2x80x9d (WO 90/11103)
c) The blunt-cannula diaphragms only can accept blunt cannulae of limited diameter and the diaphragm itself cannot be provided in the widths required to cover variously sized bottle tops, injection ports, and collection tubes without unacceptably compromising diaphragm integrity. As stated by the inventors (WO 90/11103) of the blunt-cannula system: xe2x80x9cTo provide for leak-free insertion, the length of the slit in the sealing member must be less than one-half the circumference of the cannula being inserted therethrough [xe2x80x94as a consequence of the greater penetrating ability of our inventive needles, the length of the slit would not so severely limit the diameter of the fluid channel when the proposed inventive needles are used] . . . . In addition, the slit length must be great enough, given the elastic limit of the sealing member, to prevent tearing during insertion.xe2x80x9d [xe2x80x94again, this should be less of a problem when a more tapered device (e.g., inventive needle) is used].
d) In order to accommodate a blunt cannula, the preslit typically extends to the surface or an indentation is produced so as to facilitate blunt cannula insertion. Either of these surface modifications may limit the effectiveness of antiseptic swabbing. Attempts to overcome this problem have entailed the addition of a potentially costly step in the manufacturing process, including covering the preslit stopper with a second member (which is to be torn by the blunt cannula).
The absolutely blunt cannulae of the Baxter and Abbott needleless systems also pose limitations. As stated above, they can be of only limited diameter (and thus can allow only limited flow rates) as they would otherwise require an unacceptably large slit in the diaphragm to allow insertion of their blunt tip. In addition, they tend to slip out of the blunt-cannula diaphragm, a problem that could be partially mitigated by increasing cannula length, but such a change would slow flow even further. Realizing the potential problems associated with a standard blunt cannula system, the inventors (WO 90/11103) note: xe2x80x9cIn accordance with further aspects of this invention, the blunt cannula may be provided with features that facilitate insertion into the injection site, enhance fluid flow or dispersion, increase tug resistance, and reduce kickback.xe2x80x9d These include: 1) the inclusion of a plurality of elongate discharge slits to improve flow which otherwise may be compromised by the cannula""s narrow diameter as well as to decrease the contact surface area so as to facilitate insertion; 2) grooves on the side of the cannula to reduce surface area; 3) a lead post to guide cannula insertion; 4) annular barbs to reduce kickback; 5) matching locking means, gripping means, and xe2x80x9cretaining fingersxe2x80x9d to secure engagement. Moreover, the use of blunt cannulae necessitates modification or replacement of existing setups, so that a blunt-cannula diaphragm is always available. The use of the prior art blunt cannula in the absence of a setup with a preslit or weakened diaphragm is virtually impossible unless one inserts a special xe2x80x9cspikexe2x80x9d adaptor. One side of the adaptor has a sharply pointed, open-tipped spike which can pierce a standard diaphragm; the other side has a preslit diaphragm. The spike must remain in place as long as the blunt cannula is used; and it must be discarded as a potentially hazardous sharp object (akin to a xe2x80x9cpenetrating but dangerousxe2x80x9d needle) once it is no longer required. To the best of our knowledge, there has been no attempt to increase cannula penetrating properties in a manner comparable to that of the present disclosure; i.e., there has been no attempt to increase penetrating capabilities by using a tapered needle (such as those claimed in the present three-part series) and thereby allowing for an inherently stronger entry point in the diaphragm.
The limitations of needleless systems are significant to the degree that the New York State Study on Needlestick Prevention Devices (in 1992) reported that two-thirds of healthcare workers felt that special training in the use of a needleless device was required and 20.3% of the workers at a major test center believed delivery was impeded with the device. Furthermore, the report noted that, because of the inability to provide blunt-cannula diaphragms for most containers (e.g. bottles, bags), xe2x80x9c. . . needles used with the system continued to be a hazard for injury. In one institution, needles continued to be used for administering heparin or saline xe2x80x98flushesxe2x80x99 while in the other hospital, in an attempt to avoid this hazard, a complicated system using multiple components was put into place.xe2x80x9d These factors led the compilers of the NYS report to conclude that blunt-cannula systems are less cost-effective than systems using traditional sharp, open-tipped needles enclosed in a plastic shield; thus, although they do not eliminate the potential to contact a dangerous needle, the report concluded that shielded needle systems produce xe2x80x9cgreater reductions in needlestick injuriesxe2x80x9d than the needleless systems. Of note, neither the NYS Study nor an Apr. 16, 1992 FDA Safety Alert (xe2x80x9cNeedlestick and other risks from hypodermic needles on secondary i.v. administration setsxe2x80x9d) recommended or even mentioned the use of an intrinsically safer needle (as opposed to a xe2x80x9csafe but nonpenetratingxe2x80x9d blunt cannula or a xe2x80x9cpenetrating but dangerousxe2x80x9d sharp needle which is extrinsically modified with a shield). This provides strong evidence that the subject matter disclosed herein, and in the applications and patents incorporated by reference, was not apparent even to experts and leaders in this field.
The present disclosure is #II of a three-part series of disclosures describing xe2x80x9cStrong Diaphragm/Safe Needlexe2x80x9d systems and the design and use of their individual components in order to bridge the gap between the Strong Diaphragm/Dangerous Needle and Weak Diaphragm/Safe Cannula extremes of the prior art. An important advantage of the present inventions is that, in contrast to the prior art, they provide healthcare worker safety while maintaining diaphragm integrity; i.e., the inventive series of needles and diaphragms avoid the need for diaphragms which are compromised to the point of having suboptimal sealing and unacceptably short shelf-lives as well as avoiding the need for sharp, open-tipped hypodermic needles or spike adaptors that pose infectious risks to healthcare workers. In most embodiments of the present disclosure, needle configurations which have not previously been recommended for diaphragm penetration (except for the suggestion of such in the inventors"" original patent, U.S. Pat. No. 5,478,328 in 1995) are employed. They pose far less risk to healthcare workers than standard hypodermic needles and can be matched with diaphragms to optimize needle/diaphragm efficiency and versatility.
The present disclosure focuses on a design process that entails the introduction of an optional additional step at the time of initial usage: the diaphragm is designed such that it can remain wholly or substantially intact until it is punctured or slit with a xe2x80x9cconvertorxe2x80x9d just prior to use with a specially matched blunt-tip, partially blunt-tip, and/or recessed-orifice xe2x80x9csafexe2x80x9d needle. Disclosure #I of this series (titled xe2x80x9cA Strong Diaphragm/Safe Needle Unit and Components For Transfer of Fluidsxe2x80x9d) describes how this may be accomplished by customizing needles and lessening the degree of diaphragm prechannelling/preweakening at the time of manufacture or irreversibly applying increased compressive pressure. Disclosure #III of the series (titled xe2x80x9cReversibly Compressed Prechannelled/Preweakened Diaphragms For Use With Blunt Cannulae and Safe Needlesxe2x80x9d) describes the reversible augmentation of compressive pressure at the time of manufacture which is relieved at the time of first clinical use (i.e., prior to the insertion of a blunt cannula of the prior art or with one of the safe needles which characterize our series of disclosures).
The convertors described in the present disclosure will be customized (with respect to features such as sharpness, length, diameter, and configuration) to provide needle/diaphragm/convertor combinations which seek to achieve our goals with respect to diaphragm function and needle safety. The sharpest component of such a system is the convertor. Handling and discarding of this device is much safer than handling a standard hypodermic needle or the aforementioned spike adaptor (that has been recommended for use with needleless systems) because, in contrast to the other devices, the convertor is not typically exposed to contaminants which pose a risk to a healthcare worker (since the convertor is used with previously unused diaphragms). As illustrated by several of the embodiments, another advantage of the use of a convertor is that it allows for the maintenance of a wholly intact (unindented, nonpierced) top surface of the diaphragm. This maintains sterility of the underlying contents and facilitates antiseptic swabbing. Even after penetration by the convertor, the diaphragm remains more resealable than after being torn by a blunt cannula. When indicated, the convertor can be constructed so as to only partially penetrate the diaphragm (as may be indicated if one wishes to maintain a vacuum in an underlying tube or vial). Although unnecessary in most embodiments, it can be lubricated so as to facilitate penetration and/or resealing; however, the indication should be far less than for traditional needlelesss systems. In addition, the convertor can be constructed so as to leave an indication (e.g., a mark or indentation) that the diaphragm has been converted.
In preliminary testing, we have shown that use of a 19-gauge pointed converting device can convert a conventional diaphragm which had been designed for use with a standard hypodermic needle to a diaphragm through which a partially blunted, recessed-orifice, 22 gauge or 24 gauge needle (but not a blunt cannula) can be inserted. Blunt cannula penetration requires conversion with a specially configured (e.g., larger diameter or slitting rather puncturing) convertor and/or by the concommitant use of a partially punctured or preweakened diaphragm. It should be noted that, while a standard hypodermic needle theoretically could be used to pierce a diaphragm, it has not been designed for, nor recommended for, this purpose. Specifically, the closed tip convertor configurations are preferable in that they minimize tearing and coring and avoid any chance of retaining an inoculum. Moreover, they can be matched with a given diaphragm and/or needle (or cannula) so as to optimize the features of the needle/diaphragm combination.
By utilizing the inventive needles (which are described below and detailed in Disclosure #I) as opposed to blunt cannulae, the present invention allows for maintenance of a smaller diaphragm opening and/or a lesser degree of diaphragm weakening. This substantially prevents unwanted communication between contents and environs, allows the inventive diaphragm to remain suitable for repeated use with regular as well as inventive needles (thereby obviating the need for multiple sets of supplies and bulky adaptors), and allows the inventive diaphragms to be constructed in a wide range of sizes (which may be adapted to meet medical needs without requiring a spike adaptor or standard sharp needle or the need for multiple stopper layers and leak-preventing valves).
The intrinsically safer inventive needlesxe2x80x94which are far more versatile than the blunt cannulae of needleless systemsxe2x80x94are achieved by customizing needles with one or both of the following:
(a) a partially blunted xe2x80x9csafexe2x80x9d tip which is sharp enough to puncture the inventive diaphragm but not sharp enough to penetrate the skin under normal clinical conditions, including incidental contact or contact during recapping;
(b) a closed tip and one or more recessed orifices to minimize exposure to a sizable inoculum should superficial skin penetration occur. The increased safety afforded by the closed tip allows for the safe use of needles which are significantly more pointed than the blunt cannula of needleless systems and thus usable with a wider range of diaphragms and in a wider range of lengths and diameters. In addition, the solid tip lacks the xe2x80x9ccuttingxe2x80x9d quality of an open-tip design and thereby should allow for more effective leak-free engagement and resealing. Moreover, to date, all reported transmissions of AIDS via puncture wounds to healthcare workers have resulted from puncture with a hollow bore device such as a traditional hypodermic needle or a broken glass tube. These present a sizeable inoculum which may be avoided with the solid-tip needles described herein.
Solid-tip needles are commercially available from many manufacturers for a variety of uses, including: spinal myelography, injection of intraspinal anesthetics, soft tissue biopsy, and perineural injections, as summarized by the present inventors in U.S. Pat. No. 5,478,328 in 1995 in which we taught that the use of a recessed-orifice needle permits the use of catheters which can be rotated to selectively overlie the needle orifice(s). No other inventor or manufacturer has even proposed the use of the recessed-orifice configuration for the purpose of healthcare worker safety, including the inventors of the following patents (U.S. unless noted otherwise): Leiter 145,217; Mitchell and Gillespie 561,059; Gillman 1,526,595; Weyl 446,818 (German); Peterson 2,097,039; Hanson 2,634,726; Gewecke 2,862,495; Morgan 1,196,601 (French); Schofield 3,181,336; Guttman 3,509,880; Jamshidi 3,882,849; Choksi 4,058,121; Sampson 4,190,048; Galindo 4,411,657; Guttman 4,413,993; Johnson 4,710,180; Sprotte 3,020,926 (German); Foran 4,767,407. These references disclose one or more of the following objectives: (1) to avoid coring of a rubber diaphragm by an open-bevel needle; (2) to minimize trauma to a patient""s tissues; (3) to decrease the likelihood of harmful intraneural injections during infiltration with local anesthetic; (4) to provide an additional orifice to allow venting; (5) to provide a special needle hub; and (6) to improve the success of intravenous cannulation. For example, Hanson (2,634,726) discloses a needle with a chisel-like point and a single recessed orifice which opens obliquely on the side of the shaft ipsilateral of the convex side of the needle point and is said to minimize the likelihood of clogging the needle and injecting a cork or rubber core into a patient. In 1983, Galindo (4,411,657) disclosed a needle with a solid tapered tip and recessed orifice introduced to decrease nerve trauma during injection of local anesthetic. In that same year, Guttman (4,413,993) claimed his recessed-orifice needle for minimizing infiltration from the cannulated vessel during intravenous infusion of fluid (even if the tip of the needle extended beyond the back wall of the vessel). In 1985, Alchas (4,537,593) introduced a recessed-orifice needle with an overlying sleeve to allow venting during transfer of liquid to or from a container. In 1987, Johnson (4,710,180) described a blunt-tipped cannula with multiple recessed orifices for injecting fat cells into the skin after an incision was made to allow cannula insertion. Sprotte (Germany No. 3,020,926) introduced a modified recessed-orifice needle for spinal anesthesia with improved flow characteristics and a lesser incidence of dural tear and postspinal headache.
Thus, the present disclosure teaches new needle/diaphragm combinations with needle designs which not only are different from standard hypodermic needles but also differ significantly from those for the Baxter and Abbott needleless systems described above. Moreover, in contrast to the one-step process which is carried out in needleless systems solely at the time of manufacture (described by the prior art), the present disclosure introduces: 1) conversion of an intact diaphragm at the time of initial use; and/or 2) a two-step process which entails partial prechannelling (e.g., partial prepiercing or partial preslitting) and/or partial weakening at the time of manufacture followed by penetration by a convertor just prior to clinical use. Thus, the diaphragm may be minimally compromised at the time of manufacture, yet readily penetrable by an inventive needle or cannula at the time of clinical use.
This disclosure also teaches a combined testing procedure which addresses both testing of diaphragm integrity and penetrability as well as relative needle safety using a combined index (described below).
A further feature of the invention is to provide a needle and diaphragm combination which is amenable to user friendly, efficient external modifications to decrease the likelihood of healthcare worker exposure to contaminated fluids even in the absence of a needle stickxe2x80x94e.g., retractable caps and sheaths disclosed in Disclosure #I (xe2x80x9cStrong Diaphragm/Safe Needle Units and Components for Transfer of Fluidsxe2x80x9d) and in U.S. Pat. No. 5,478,328, incorporated by reference.